Self-reversing exducer for gas turbines



Oct. 31, 1961 c. LA FOREST MILLER 3,006,604

SELF-REVERSING EXDUCER FOR GAS TURBINES Filed Dec. 2, 1958 2 Sheets-Sheet 1 INVENTOR. CHARLES LA FOREST MILLER ATTORNEY Oct. 31, 1961 0. LA" FOREST MILLER 3,006,604

SELF-REVERSING EXDUCER FOR GAS TURBINES Filed Dec. 2, 1958 2 Sheets-Sheet 2 CHARLES LA FOREST MILLER H09. 4 TO EXhOUSf BY To Exhaust United States Patent 0 ,6 SELF-REVERSING EXDUCER FOR GAS TURBINES Charles La Forest Miller, 5108 Seventh Road S., Arlington, Va. Filed Dec. 2, 1958, Ser. No,- 777.797 2 Claims. (Cl. 253-52) (Granted under Title 35, U.S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to reversible gas turbines and more particularly to such gas turbines which operate efficiently in either direction of rotation of the turbine shaft.

The principal object of the invention is to provide reversible gas turbine structure whereby substantially equal power is attained in either direction of rotation of the turbine shaft.

Another object of the invention resides in novel arrangement for reversing the flow of exduced gases from a gas turbine power plant.

Another object is to modify the turbine shaft of a power plant and provide for the ready reversal of gases exduced therefrom.

FIGURE 1 is a longitudinal sectional view of a preferred embodiment of the invention; and

FIGURE 2 is a view taken substantially along line 2-2 of FIGURE 1 showing portions in section; and

FIGURES 3 and 4 are developed fragmentary views of the device of FIGURE 1.

Referring to the drawings and particularly to FIGURE 1, an inlet nozzle is provided for effecting the rotation of a turbine shaft 12 To this end, an impeller wheel of suitable design is indicated generally at 14 and is fixedly mounted on shaft 12. Rotation of the shaft 12 is effected through an irnpelling medium which is supplied by nozzle 10 and impinges on blades 16 which are disposed radially of the impeller wheel 14. The nozzle 10 may be pivoted or a second nozzle could be provided for the purpose of reversing the direction of rotation of shaft 12 since it is essential to the invention that shaft 12 be rotated in either direction.

A tubular power shaft 18 is concentrically mounted about the turbine shaft 12 and is arranged to rotate therewith. To this end, a plurality of radial pins 20 extend from the shaft 12 in circumferentially spaced relation and a plurality of circumferentially spaced slots 22 are provided in the tubular power shaft 18, each slot for receiving one of the pins 20, as shown in FIG. 2. As shown in FIGS. 3 and 4, both the pins and the slots are arranged in a pair of off-set or axially spaced rows and each slot is provided with opposed abutments or stops 24 and 26 which limit the movement of the pins 20 in the slots. In effect, the pin and slot arrangements provide lost motion connections permitting the shaft 12 to rotate through a small arc independently of the shaft 18 until the pins 22 contact one or the other set of the abutments 24 or 26 depending on the direction of rotation of shaft 12. When the pins 20 contact one set of the abutments the outer power shaft 18 is caused to rotate in the same direction in which the shaft 12 is being rotated.

The off-set arrangement of the pin and slot connections is used in order not too greatly to weaken the outer tubular shaft 18 which would probably be the case if the slots 22 were on the same circumferential line and of substantial length as shown in FIGS. 3 and 4. As shown in FIG. 2, the outer ends of the pins 20 receive blades which extend outwardly of the power shaft 18 and are arranged in alternate sets 30 and 32. The transverse cross-sectional shape of the blade in one set differs from "ice that of the blades in the other set, but as will be seen in FIGS. 3 and 4 they occupy or rotate through a common circumferential zone determined by the transverse shape .or thickness of the blades. Also, as will be seen from F165. 3 and .4, adjacent blades 30 and 32 define, by their opposed concave and convex side faces, auxiliary fluid paths which are disposed at the outlet ends .of passageways 56 and which deflect the impelling fluid in a direction generally opposed to the direction of rotation .of the shafts :12 and 18. As indicated in FIGURE 3, each blade 30 has a leading edge 3.4, concave side faces 36 and 3,8 and rear face 40, While each blade 32 has a vertical flat front face .42, convex side faces 44 and .46, and a wertical trailing edge 48.

Baffles 50 are fixedly mounted axially of the power shaft 18 and extend radially therefrom. An end space 52 is formed between the front ends of the bafiies 50 and the turbine wheel 14 and an end space 54 is formed between the rear end of the baffles 50 and the blade sets 30 and 32. A plurality of axial passageways 56 are formed between the batfles 50 as shown in FIGURES 3 and 4 which serve to channel impelling fluid from nozzle 10 to the sets of exducer blades 30 and 32. The baflies are shown as having a leading edge 58 and outwardly flaring side faces 60 to provide the general design of that shown in FIGURE 3, an outer longitudinal edge 62, and rear face 64 which interconnects the side faces 60. An exhaust compartment is formed by a portion of a shroud S which, although not completely shown, would enclose the baflles 50 and blades 30 and 32 for receiving the exduced gases. At 74 is indicated a bearing arrangement for conveniently mounting the shafts 12 and 18 for rotation.

Rotation of the turbine shaft 12 causes the exducer blade control or power shaft 18 to rotate but due to the lost motion effected by the connection between the pins 20 and the slots 22, the shaft 18 has a time lag before it changes its direction of rotation and causes the exducer blades 30 and 32 to impart the change of direction to the exduced gases.

In FIGURE 3 of the drawing, the power shaft 18 will be understood to be rotating in the direction indicated by the arrowed broken line and the exduced gas will have a relative swirl vector opposite to this direction of rotation as shown by the arrowed full lines. In FIGURE 4 the power shaft 18 will be understood to be rotating in the reverse direction from that of FIGURE 3 and the exduced gas has a relative swirl vector opposite this direction of rotation.

Although there is herein shown and described a preferred embodiment of the invention, manifestly it is susceptible of modification without departing from the spirit and scope thereof. It is, therefore, not to be understood as limiting the invention to the precise form herein disclosed, except as may be so limited by the appended claims.

I claim:

1. A gas turbine comprising an inner drive shaft having an impeller fixedly mounted thereto at one end, fluid means for selectively rotating said inner drive shaft in either direction, an outer tubular power shaft mounted concentrically of the drive shaft, said outer power shaft having one end disposed adjacent the impeller and its other end disposed beyond the other end of the inner drive shaft, a plurality of bafiles fixed to and extending axially along the outer wall of the power shaft providing fluid passageways therebetween, each of said passageways having a fluid inlet at said one end of the power shaft adjacent the impeller and an outlet at said other end of the power shaft, a group of equally spaced slots in said power shaft extending circumferentially thereof and a group of equally spaced blades extending radially and circumferentially of the inner drive shaft and having supporting means extending through said slots and secured to said shaft, said slots and blades being equal'in number providing agroup of blade and slots lost motion connections between the shafts, alternate blades of 'said group having opposed faces of concave shape and other blades of the group having opposed faces of convex shape, adjacent blades of the group providing a cooperating pair of concave and convex faces, said lost motion connections being constructed and arranged on rotation of the inner drive shaft in one direction to position cooperating pairs of faces adjacent the outlet of each passageway for deflecting fluid from the passageways in the opposite direction from that of said one direction of rotation of the inner driveshaft. and on rotation of the inner drive shaft in the other direction to position other cooperating pairs of faces adjacent the outlets of the passageways for deflecting the fluid from the passageways in the opposite direction to that of said other direction of rotation of the inner drive shaft.

2. A gas turbine as in claim 1, further characterized by the slots of said group having a length equal to the width of the passageways to permit the cooperating pairs of concave and convex faces of the blades to be positioned in alignment with the passageways.

References Cited in the file of this patent UNITED STATES PATENTS 

